Modern electronic devices are networked. For life support systems medical technology and in aerospace industry, such networks are also used to compensate the failure of one participant by functions from other network stations. But the failure of line connections must not lead to a significant functionality loss of the systems. For the developing engineers, this means a significant expansion of the functionality and thus the test plan. A structured software integration test must of course take into accout each and every possible interference and error in the networt structure and thus prove the correctness of the system response. Just how are broken wires or loose contacts are to be presented in the test? And how can the behavior of the target system eventually be examined?